1. Field of the Invention
This invention relates to a disk cartridge for accomodating therein an optical disk, a magnetic disk or the like, which is provided with a dust-proof sliding shutter for a disk exposing window portion of the disc cartridge.
2. Description of the Prior Art
There has conventionally been proposed a disk cartridge provided with a dust-proof sliding shutter for a disk exposing window portion of the disk cartridge which is constructed as shown in FIGS. 1 and 2 (disclosed in Japanese Laid-open Patent Gazzette No. 58-169379).
This disk cartridge has a window portion 3 for exposing a part of a disk 2, arranged on a flat portion of a cartridge half 1 thereof, and a rail portion 4 arranged on one side edge portion of the cartridge half 1 along an external edge of the window portion 3. There is provided a dust-proof shutter 5 which moves parallelly along the rail portion 4 to open and close the window portion 3. A torsion spring 6 is stretched between one side edge 5a of the dust-proof shutter 5 and a corner portion 1a of the cartridge half 1, which spring 6 always urges the dust-proof shutter 5 by its biasing force toward the closing direction of the window portion 3, wherein the dust-proof shutter 5 is kept in its closing state by its other side edge 5b being abutting against a stopper 7 projectedly provided on the cartridge half 1 at a location corresponding to an end position of the rail 4.
In such a conventional disk cartridge constructed as mentioned above, the torsion spring , which biases the dust-proof shutter 5 toward the window portion 5, flexibly moves all over the space between the side edge 5a of the dust-proof shutter 5 and one side wall of the cartridge half 1, namely a space a in the corner portion 1a of the cartridge half 1, by opening and closing movements of the dust-proof shutter 5, so that it is impossible to provide a projected boss used for screwing and integrating the cartridge halves 1 in the space a. Accordingly, the two cartridge halves should be bonded by ultra-sonic soldering or a bonding agent. If the cartridge halves 1 are bonded as mentioned above, it becomes difficult to exchange the disk accomodated therein and further impossible to reproduce the cartridge halves.